Breeding Biology of Grassland Birds in Western New York: Conservation and Management Implications

Declining grassland breeding bird populations have led to increased efforts to assess habitat quality, typically by estimating density or relative abundance. Because some grassland habitats may function as ecological traps, a more appropriate metric for determining quality may be breeding success. Between 1994 and 2003 we gathered data on the nest fates of Eastern Meadowlarks (Sturnella magna), Bobolinks (Dolichonyx oryzivorous), and Savannah Sparrows (Passerculus sandwichensis) in a series of fallow fields and pastures/hayfields in western New York State. We calculated daily survival probabilities using the Mayfield method, and used the logistic-exposure method to model effects of predictor variables on nest success. Nest survival probabilities were 0.464 for Eastern Meadowlarks (n = 26), 0.483 for Bobolinks (n = 91), and 0.585 for Savannah Sparrows (n = 152). Fledge dates for first clutches ranged between 14 June and 23 July. Only one obligate grassland bird nest was parasitized by Brown-headed Cowbirds (Molothrus ater), for an overall brood parasitism rate of 0.004. Logistic-exposure models indicated that daily nest survival probabilities were higher in pastures/hayfields than in fallow fields. Our results, and those from other studies in the Northeast, suggest that properly managed cool season grassland habitats in the region may not act as ecological traps, and that obligate grassland birds in the region may have greater nest survival probabilities, and lower rates of Brown-headed Cowbird parasitism, than in many parts of the Midwest.

Convergent evolution: floral guides, stingless bee nest entrances, and insectivorous pitchers

Several recent hypotheses, including sensory drive and sensory exploitation, suggest that receiver biases may drive selection of biological signals in the context of sexual selection. Here we suggest that a similar mechanism may have led to convergence of patterns in flowers, stingless bee nest entrances, and pitchers of insectivorous plants. A survey of these non-related visual stimuli shows that they share features such as stripes, dark centre, and peripheral dots. Next, we experimentally show that in stingless bees the close-up approach to a flower is guided by dark centre preference. Moreover, in the approach towards their nest entrance, they have a spontaneous preference for entrance patterns containing a dark centre and disrupted ornamentation. Together with existing empirical evidence on the honeybee's and other insects' orientation to flowers, this suggests that the signal receivers of the natural patterns we examined, mainly Hymenoptera, have spontaneous preferences for radiating stripes, dark centres, and peripheral dots. These receiver biases may have evolved in other behavioural contexts in the ancestors of Hymenoptera, but our findings suggest that they have triggered the convergent evolution of visual stimuli in floral guides, stingless bee nest entrances, and insectivorous pitchers.

Efficacy of neem (Azadirachta indica) formulations on biology of root-knot nematodes (Meloidogyne javanica) on tomato

Second stage juveniles of Meloidogyne javanica were exposed to aqueous extracts of neem crude formulations (leaves and cake) at 10%, 5%, and 2.5% w/v and a refined product, Aza at 0.1% w/v. The 10% extracts of neem leaf and cake caused 83% and 85% immobility and 35% and 28% mortality, respectively. Aza caused neither immobility or mortality of juveniles. When egg masses were placed in extracts of these formulations, hatching did not occur at all the concentrations (10%, 5%, 2.5% and 1.25% w/v) of the crude formulations. When the treated egg masses were returned to water, the eggs resumed hatching. Aza did not affect the nematode hatching. In glasshouse experiments, soil application of neem formulations significantly reduced the invasion of tomato roots by root-knot nematodes but once the nematodes managed to invade them, no effect detected on their development. Soil applications of Aza at 0.05% and 0.1% w/v significantly reduced the invasion and delayed development of nematodes within tomato roots whereas 0.025% did not. There were significantly fewer egg masses on tomato roots exposed to single egg mass in neem amended soil as compared to control. (C) 2007 Elsevier Ltd. All rights reserved.